PERMEATION OF AQUEOUS SODIUM CHLORIDE SOLUTION THROUGH CELLULOSE ACETATE MEMBRANE IN REVERSE OSMOSIS
| Autor: | Hiroaki Tonami, Kazumasa Kataoka, Tetsuya Sakai |
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| Rok vydání: | 1978 |
| Předmět: | |
| Zdroj: | Sen'i Gakkaishi. 34:T113-T120 |
| ISSN: | 1884-2259 0037-9875 |
| DOI: | 10.2115/fiber.34.3_t113 |
| Popis: | In the reverse osmosis, two types of flow through cellulose acetate membrane exist: one is the diffusion type flow of water driven by the effective pressure difference (ΔP-Δπ), where ΔP is the hydraulic pressure difference and Δπ is the osmotic pressure difference, and another is the capillary type flow driven by the hydraulic pressure difference.In this paper, a closer investigation on the capillary type flow has been made, while a few investigators discussed on that flow.Permeation of aqueous sodium chloride solution through two kinds of cellulose acetate membrane has been studied changing the applied pressure and the concentration of the feed solution widely.Results are as follows.Following empirical equations for volume flux Jv and solute molar flux Js which are applicable in the experimental ranges of pressure and salt concentration are obtained:Jv=Aoexp(-απf) (ΔP-Δπ)+Boexp(-bπf)ΔPJs=ks+CfθBoexp(-bπf )ΔPWhere Ao•exp(-a πf) is the permeability of water by the diffusion type flow, Bo•exp(-bπf) is the permeability by the capillary type flow, πf is the osmotic pressure of the feed solution, Cf is the concentration of the feed solution, ks, is the solute molar flux of diffusion type flow and θ corresponds to the selectivity of the capillary type flow.Using these equations, solute rejection at ΔP is expressed as follows: Where σv is the reflection coefficient obtained from the relation between ΔP and Δπ at Jv=O.Above equation shows that Rej increases with applied pressure to an ultimate value, designated as σr.The relation between σr and σv isσr=1-(1-σv)θWhen capillary flow has no selectivity, i.e. θ=1, σr=σvIn our experiments, θ is lower than unity, so that σr, becomes greater than σv. |
| Databáze: | OpenAIRE |
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